The present invention relates to a storage system, a file migration method, and a computer program product.
In recent years, as a storage system management method, data life cycle management (DLCM) has been gathering attention. DLCM is a concept of achieving cost-effective data management by managing data migration between storage systems in accordance with the data value changing over time. For example, an e-mail system is considered as a core system for businesses, so a high-end storage system with high performance and reliability is required. Since e-mail several weeks old decreases in access frequency, the data will be migrated from a high-end storage system to a near-line storage system. A near-line storage system, compared to a high-end storage system, is inferior in performance and reliability, but has the advantage of being low cost, and is also promptly accessible whenever needed. After one to two years have passed since the data migration to the near-line storage system, the data is moved to a tape medium to be kept in a vault. Data migration management is important in reducing data management costs according to the idea of DLCM.
In a multi-tiered storage system, the data migration operation is simplified by logically defining and categorizing storage resources as storage tiers (Tiers) in accordance with business requirements and purposes. For example, when old e-mail data is moved to a low-cost storage system, a storage tier is logically defined under the name of an arbitrary name such as “low-cost storage” or “e-mail data storage,” making it possible to easily search optimum storage resources using that storage tier definition in conducting a data migration.
Also, for enhancing the convenience of data migration management, file-based data migration is getting more attention recently, in addition to block-based data migration. For example, JP-A-2004-295457 refers to a technique of file-based data migration conducted between disks of different tiers.